Double-bulb ballast lamp



July 28, 1925.

' 1,547,701 P. T. WEEKS DOUBLE BULB BALLAST LAMP Filed June 25. 1921' WITNESSES: J INVENTOR' PM T WEB/r5.

- BY Y 'ATTORNEY I 10 and particularly to devices- Patented July 2 8, 1925.

Umrao s'r PAUL 'r. wnnxs,

F CALDWELL, NEW JERSEY, ASSIGNOR TO WESTINGHOU SE COMPANY, A CORPORATION OF PENNSYLVANIA.

LAMP

DOUBLE-BULB BALLAST LAMP.

Application filed June 25,

To all whom it may concern: Be it known that 1, PAUL T. Wrens, a citizen ofthe United States, and a resident of Caldwell, in the county of Essex and State of New Jersey, have invented a new and useful Improvement in DoubleBulb Ballast Lamps, of which the following is a. specification.

My invention relates to control devices of the type known as ballast devices or ballast lamps which comprise resistance elements, having high temperature coefiicients of resistance and disposed in gas that is inert with respect 5 to the resistance element.

One object of my invention is to provide a ballast device comprising two bulbs, one of which shall have a conducting element dis-, posed therein. Another object of my invention is to provide a ballast device, of the above-indicated character, in which the bulbs shall be connected by a small capillary tube in order to preventundue circulation of the gas between the bulbs.

Another object of my invention is to providev a device, of the above-indicated character, that shall be simple and economical in construction and reliable and effective in its operation.

Ballast lamps consisting ordinarily of filaments of'iron wire in atmospheres of hydrogen have been used to a considerable extent in; connection with Nernst glowers for counteracting the negative temperature --coefiicient of resistance of the glowers and have been used with other devices for maintaining a substantially constant current,

i notwithstanding variations in the value of 40 the supply voltage. As ordinarily constructed, these lamps have comprised a filament mounted in a small bulb somewhat like. that of an ordinar incandescent lamp.

While constructing bulbs of this type, it .has been observed that a smaller value of current is required to heat thefilament to a predetermined temperature when the lamps are on manifold then after the lamps have been sealed and removed, although the gas pres sure was substantially the same in both instances. I

The explanationappears to be that, when, the lamp is on the pump, a portion of the gas is forced out of the bulb during the exthe potential difference creased current-regulating efi'ect renders a the pump and still connected to the 1921. Serial No. 480,487.

pansion thereof by reason of the heated filament and that the density of the gas surrounding the filament is, therefore, reduced and tends correspondingly to decrease the cooling eilect upon the filament.

' In order to utilize this effect to make a sensitive ballast lamp that will operate over a relatively wide range of voltage,-I provide a lamp embodying two bulbs that are connected by a capillary tube having a small bore, and dispose the resistor element within one of the bulbs. c If the value of current traversing the ordinary ballast lamp of the single-bulbtype tends to increase, the voltage across the terminals of the filament or resistor increases by-reason. of the increased resistance resulting from the heat that is developed therein, the amount of heat that is developed in a filament of such a ballast lamp increases considerably for a relatively small change in the value of current traversing the same.

The auxiliary bulb serves as an expans sion chamber and operates in a manner similar to that of the manifold mentioned above. .3 In a device of this type, as the gas is heated by the filament, it is forced from the bulb containing the filament into the auxiliary bulb. The capillary tube prevents circulai tion of the gas. By means of such a con-' 5 struction, the temperature of the gas in the main bulb will be considerably greater than the temperature of the gas in the auxiliary. bulb. Although the pressure in the tw6 bulbs will be the same, the density of the. gas surrounding the filament will be less than the density of the gas in the auxiliari bulb. The dissipation of heat from the filaj ment will be correspondingly decreased by reason of the decreased density of the gas surrounding the same, and a rapid increase in the temperature of the filament and in across the terminals thereof will result. The consequent incontrolling'device of this character relative- 1y sensitive.

On one device of this type, the potential difference across theterminals of the filament increased from 1.6, volts to 3.6 volts with substantially no increase in the cur rent, whereas, in a single-bulb ballast device employing the same filament, an increase of substantially 5% of thev'alue of current is necessary to effect the corresponding in- -crease in the potential difi'erence'between the terminals of the resistor.

diagram is a diagrammatic view of an electrical circuit containing a control device em--, bodying my invention. 7

A source 1 of energy is connected to a circuit 2 vfrom which energy is received b a constant-current device 3. The current t at traverses the device 3 is controlledby a ballast-controlling device i to maintain the valuev of that current constant. The device 4 comprises a main bulbfi, anauxiliary bulb 6 and a capillary tube7, having a small bore, connected therebetween.

.-The bulbs 5 and' flj contain a relatively inert/gas, such as hydrogen or nitrogen, I

.;-and the bulb 5 also"-has-di,sposed therein a v f filament resistor S-of [conducting material having a relatively high temperature coeflicient of resistance.

It is evident that-the characteristics of a device of this type will be largely afi'ected by the relative sizes of the two bulbs, the

relation between the dimensions .and the shape of the bulbs, the size and length of sponding valuefof current. 1 My invention is not limited to the specific structure or to the specific arrangement of the various elements, since modifications may be made therein within'the spirit and scope of the invention, as set forth in the appended claims.

I claim as my invention 1. A controlling device comprising a bulb containinga conducting element of a relatively-high temperature coefficient of .re-

sistance and fluid and means whereby the, 4

tions within the bulb.

density of the fluid surrounding the conducting element may be varied.

2.A controlling device comprising a bulb containing a conducting element andfluid and means whereby the density of the fluid surrounding the conducting element may beautomatically varied in accordance temperature of the element. I

3. A controlling device comprising a bulbwith the containing a conducting element and fluid and'means whereby the-density of the fluid surrounding the conducting element may be I automatically varied in accordance'w'ith the temperature of the fluid. 4. 1A controlling device comprising a chamber containing a heat developing member, a fluid surrounding the member and an auxiliary chamber. adapted to receive a temperature of the filament'for the correportion of the fluid normally surrounding the heat develo .ing member. -The single figure of the accompanying 5. A contro ling device comprising a chamber containing a heat developing member, a fluid surrounding the member and means adaptedto receive a portionof the fluid normally surrounding the heat developing member.

6. A controlling device comprising a chamber containing a heat developing member, a fluid surrounding the member and an auxiliary chamber to receive a portion of the fluid normally contained in said first mentioned chamber to efiect a reduction in the density of the fluid surrounding the heat developing member. I e

7. A controlling device comprising :1 chamber containing a heat developing member, a fluidsurrounding the member and of the means for controlling the density fluid surrounding theheat developing member in accordance with the temperature of that member.

8. A controlling device comprising a chamber containing a heat developing member, a fluid surrounding the 'member and means for controlling the density of the fluid surrounding the heat developing member in accordance with the temperature of the fluid.

9. A controlling device containing a main chamber, an auxiliary chamber, anf

element in said main chamberhaving a 'higl1 temperature coefliclent of res stance, a gas eous. environment within sad d chambers and a capillary communication between said chambers whereby when said element is heated the density of said gas surrounding the element will become less than the density of the gas inthe auxiliary chamber and 11. A controlling device comprising'a receptacle, a current-heated member therein, a

fluid surroundingthe member and means for controlling the relative heating of the current-heated member by di'fi'erentvalues of current.

12-. A controlling device comprisin a re-' ceptacle, .a current-heated member therein, a fluid surrounding the member-and means for controlling the cooling effect of the fluid.

13. A controlling device comprising a, bulb, a current-heated member; therein, a fluid surrounding the "member and means for controllin .pacity of the uid.

the heat-transferring ea- PLA- controlling device comprising 'a bulb, a current-heated member therein, a

fluid surrounding the member and means for decreasin the heat-transferring ca 'pacity of the uid as the temperature of the heated member increases.

15. A resistance device comprising a gas filled bulb 'containin .a filament and con "hydrogen filled bulb containing a resistance ement and connected to another bulb by a capillary tube whereby some of the gas in the first .bulb flows into the other bulb, thereby decreasing the density of the gas in the first bulb, when the resistance element is heated.'

17. In combination with a device requiring a substantially uniform current, a con trolling device comprising two bulbs connected by capillary means.

18. In combination with a device 'requin illg a substantially uniform current, a. controlling device comprising two bulbs connected by a capillary 'tubeand'an electrical conducting member disposed in one bulb.

19. In combination with a device requiring a substantially uniform current, controlling means comprising a fluid filled bulb' containing a conducting element anduneans serving fluid when the conducting element is heated.

20. In combination with a device requiring a substantially uniform current, controlling means comprising a bulb containing a conductive filament surrounded by a fluid and means whereby, the density of the fluid surrounding the conducting filamentmay be automatically varied when the filament .be-

comes heated.

21. In combination with a device requiring a substantially uniform current, a ballast resistance comprising a chamber filled with the fluid and containing a heat as an overflow reservoir for thedeveloping member in series with the device and means controlling the density of the fluid in accordance with the temperature of the heat developing member.

22. In combination with a device requiring a substantially uniform current, a resistance device comprising a bulb, a filament therein, a fluid surrounding the filament and means associated with the bulb for modifying the heat losses "from the filament when the same is heated.-

23. In combination with a device requiring a substantially uniformicurrent,"a ballast resistance comprising a'gas filled bulb enclosing a current-heated resistance memher and means for controlling the heat transferring capacity of the gas according to the temperature of the heated member.

24. In combination with a device requiring a substantially uniform current, a ballast resistance'comprisingtwo vessels hav ingan environment of a given substantially uniform density, a resistance element in one of said vessels in series with said device and acapillary-communication between said vessels whereby the density of the environment in the two vessels becomes unequal when said resistance element raises the temperature of the environment within one of said vessels. .7

25. In combination with a device requiring a substantially uniform current, a ballast resistance inseries therewith comprising a lower bulb containing a resistance element and connected to an upperqbulb by a capillary tube which prevents circulation of a fluid in said bulbs whereby, when the device'is operated, the fluid in the lower bulb is at a higher temperature and of ag lower density than that in the upper bulb.

In testimony whereof, I .have hereunto subscribed my name this 10th day of June 1921. 1 V

i PAUL '1 WEEKS. 

